On 06/01/2011 02:35 PM, Sasha Levin wrote: > On Wed, 2011-06-01 at 09:41 +0800, Asias He wrote: >> On 06/01/2011 12:32 AM, Sasha Levin wrote: >>> On Tue, 2011-05-31 at 10:18 +0300, Pekka Enberg wrote: >>>> On Tue, May 31, 2011 at 2:53 AM, Asias He <asias.hejun@xxxxxxxxx> wrote: >>>>> TAP based network performance with ioeventfd >>>> >>>> Heh, so how did it look _before_ ioeventfd? Did performance improve >>>> and how much? >>> >>> Asias, did you use TCP or UDP values as bandwidth in your previous test? >>> >> >> These commit log have the performance test result before ioeventfd. But >> the UDP one is missing. >> >> commit 739ddbb3b0fe52aa90a84727a6e90da37ce7661b >> commit 4ed38b41fc034cfb51fec2004f523fe98faa27f6 >> >> >> Netpef test shows this patch changes: >> >> the host to guest bandwidth >> from 2866.27 Mbps (cpu 33.96%) to 5548.87 Mbps (cpu 53.87%), >> >> the guest to host bandwitdth >> form 1408.86 Mbps (cpu 99.9%) to 1301.29 Mbps (cpu 99.9%). >> >> >> Anyway, I did another test and post the result here: >> >> Test shows host -> guest TCP performance drops from 6736.04 to 5562.25. >> guest -> host TCP performance dumps from 1572.51 to 1731.55. > > That's quite strange. I wasn't expecting any changes with our current > network code: Our RX thread is blocking on readv() most of the time, so > it doesn't get affected by IRQ/ioeventfd signals at all, and the TX > thread should get signaled to wake up just once or twice when the stream > starts - after which the virtio ring should be full with data. > > I installed netperf and ran the tests (full results are below), guest -> > host TCP changed from 1862 to 2567 and host -> guest TCP changed from > 7716 to 8065. I have no idea why I am seeing this regression in my box. However, your change should not introduce this regression. -- Best Regards, Asias He -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
